Method and arrangement for controlling an internal combustion engine of a motor vehicle by operating on fuel metered to the engine and/or on the ignition angle of the engine

ABSTRACT

The invention is directed to a method and an arrangement for controlling a motor vehicle having a plurality of component systems. A first one of the component systems is a motor control system. An interface position is defined between various ones of the component systems and faces toward the first component system. The interface position operates on the basis of the torque generated by the motor. The component systems exchange data via the interface position with respect to this torque for controlling the motor vehicle.

This is a divisional of application Ser. No. 08/157,993, filed on Nov.26, 1993, now U.S. Pat. No. 5,558,178.

BACKGROUND OF THE INVENTION

Modern motor vehicles are characterized by a plurality of electronicsystems such as electronic injection and ignition controls and/or ABSsystems. Additional electronic systems must be introduced in order to inthe future satisfy ever increasing requirements as to: compatibilitywith respect to the environment, wear, safety and/or comfort of themotor vehicles. The most important systems are the following: electronicengine power control systems (the so-called electronic gas system),road-speed control systems, anti-skid or engine braking torque controlsystems (ASR/MSR) and/or electronic transmission control systems as wellas chassis control systems, steering systems including electronicrear-wheel steering, control systems for maintaining distance betweenmotor vehicles, navigation systems and/or traffic guidance systems.

In this connection, it is to be noted that the above-mentioned componentsystems intervene at least in several subranges of their function on theoutput power of the motor vehicle, for example, the transmission controlduring gear shifting operation, the ASR-system for anti-skid control, acontrol system for controlling the distance to a motor vehicletravelling forward of the subject vehicle and the like. This furtherincreases the complexity of the total system for controlling the motorvehicle. An optimal cooperative relationship between the componentsystems is necessary, however, to obtain a satisfactory control of themotor vehicle. It is an object to reduce the cross coupling between theindividual component systems and thereby obtain an independentapplication and control of each component system.

A first step in this direction is disclosed in U.S. Pat. No. 5,351,776.Here, and proceeding from a driver command, a hierarchically arrangedsystem structure is proposed wherein interface positions are definedbetween the individual logic component systems via which data withrespect to one of the variables are transmitted. This variable is to beadjusted by the next-lower hierarchical level. Data with respect to amotor torque desired value are transmitted for adjusting the motor powervia the control of the air supplied, the fuel metered as well as theignition time point. A detailed description of this interface position,which is directed toward the motor control system, is not provided inthe above-mentioned patent application.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method and an arrangementfor controlling a motor vehicle with at least one electronic componentsystem in addition to the motor control system. An interface position isprovided in the direction toward the motor control system which can beoperated by all available component systems and which can be appliedindependently of motor types as well as independently of the variablesavailable for influencing the motor and independently of the componentsystems communicating with the motor control system.

This is achieved in that at least values from at least one componentsystem in at least one operating state are transmitted to the motorcontrol system. These values are with reference to a variable which canbe influenced by adjusting at least one of the power parameters of themotor and the variable is supplied by the motor control system byadjusting at least one of the power parameters present. The variabledefines a parameter which is either a measure for the power capacity ofthe motor, a measure for the torque supplied by the motor or the powersupplied by the motor.

German patent application 42 32 974.4 discloses that a desired motortorque can be supplied by influencing the air supply and the ignitionwhile computing and adjusting the combustion torque necessary therefor.

U.S. Pat. No. 5,484,351 discloses that lost torque (torque attributed tofriction and bearing play, for example), torque attributed to additionalconsumers and corrective torques (for example, of an idle controller)are considered when adjusting the motor torque and to adapt these torquecomponents, that is, to consider possible changes of these torquecomponents.

The procedure provided by the invention provides a unified interfaceposition to the motor control system which reduces cross couplingbetween the component systems and permits an independent application andcontrol of each component system.

It is especially advantageous with respect to this procedure provided bythe invention that the suggested interface position is configured so asto be modular so that the interface position is unaffected when asubstructure (for example, electronic control of the air supply) of themotor control is eliminated.

It is especially significant that the interface position is soconfigured that communication between different control system types ispossible without influencing the interface position. The differentcontrol systems can also be made by different manufacturers.

With the configuration of the interface as provided by the invention, afine metering of the following is advantageously provided: the powercapacity of the motor, the torque supplied by the motor or the powersupplied. Also, a reduction of the additional exhaust gas load isprovided for which occurs from component systems when intervening on themotor.

It is further advantageous that structure and characteristic fields aswell as characteristic lines for realizing the interface position in theregion of the motor control system can be simplified in dependence uponthe requirements as to precision.

The interface position according to the invention is especiallyadvantageous in combination with an ASR intervention and/or an MSRintervention by suppressing selected injection pulses and/or correctingthe ignition angle and/or during an intervention in a motor by atransmission control during the gear-shifting operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the drawingswherein:

FIG. 1 is a block circuit diagram of the configuration of a moderncontrol system for a motor vehicle;

FIG. 2 is a circuit block diagram of an embodiment of the interfaceaccording to the invention;

FIG. 3 shows a realizable form of the interface position as a blockcircuit diagram;

FIG. 4 shows the reduced interface position when only an interventionwith respect to the ignition is intended;

FIG. 5 is a reduced interface position for an exclusive intervention inthe metering of fuel; and,

FIG. 6 is an interface position when there is an intervention withrespect to the ignition and with respect to the metering of fuel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 shows a control system for a motor vehicle as an overview blockcircuit diagram. The system includes a control apparatus 10 forcontrolling the motor and is equipped with a unit for fuel metering 12,a unit for air metering 14 and/or a unit for adjusting ignition 16. Inaddition, the following are provided: a control unit 18 for controllingan automatic transmission, a control unit 20 for controlling the brakesas well as for carrying out an anti-skid control or motor braking torquecontrol and/or a control unit 22 for controlling the driving dynamic orfor adjusting the chassis. These control units are connected to eachother via the line system 24 (communication system) such as via theso-called CAN-bus so that the units can mutually exchange data.Measuring devices 30 to 32 are connected to the line system 24 viacorresponding lines 26 to 28. The measuring devices 30 to 32 detectoperating variables from the engine, drive train and/or motor vehicle.The detected operating variables comprise generally known operatingvariables such as motor rpm, motor temperature, battery voltage, wheelrpm, road speed, output rpm, transmission position, turbine rpm, etcetera. Also, actuators 38 to 40 for carrying out the various controlfunctions are connected to the line system 24 via respective lines 34 to36. These control functions include, for example, fuel injectionsystems, ignition systems, electrically controllable throttle flaps,positioning devices of an automatic transmission such as clutches,actuating devices for the chassis (electrically controllable springdamping elements) as well as pressure systems for brake actuation.

The control units shown in FIG. 1 carry out the functions assignedthereto while detecting the operating variables necessary therefor andform control values for the various actuating units. Component functionsare necessary for the foregoing such as in combination with an anti-skidor motor braking torque control, a transmission control for controllingthe gear-shifting operation as well as interventions in the drive powerof the drive unit when controlling the chassis and thereby interventionsinto the motor control system 10. The communication between the controlunits 18 to 22 and the motor control system 10 is determined by aninterface position to be provided. A unified interface position having amodular configuration and with the above-mentioned advantages isprovided by the invention described below.

FIG. 2 shows the connection to the motor control system. Theconfiguration described is an embodiment of the invention which definesthe most sophisticated interface positions possible in the context ofthe invention.

In FIG. 2, the motor control system 10 is shown at right which isconnected via the line system 24 to the individual control units orcomponent systems 18 to 22 which are combined in the control system 42,represented by the broken line. Data is exchanged between the controlsystems via the line system 24 for carrying out the control functions.First, a desired value is needed which defines a measure for a variablecharacterizing the power output or power capacity of the motor. Thisdesired value can, for example, be a desired clutch torque (mokupdes)which occurs at the crankshaft of the motor. Alternatively, a desiredvalue for the indexed torque (combustion torque movdes) can betransmitted. The indexed torque or combustion torque is that torquewhich is developed by the action of the piston. The relationship betweenthe combustion torque and the clutch torque is provided by a simpleconversion and the combustion torque corresponds to the clutch torqueplus the sum of the lost torque moverl, which is consumed by the mass ofthe drive unit, and further torque amounts from consumers mona. Inaddition, a desired value for the power of the motor (Pdes) can also betransmitted.

Status data with respect to control units 18 to 22 and/or the drivercommand mokupf are supplied to the motor control 10 in dependence uponthe configuration of the motor vehicle control system. If the motorcontrol system includes processing the driver command, then thetransmission of this data can be omitted or the transmission can takeplace from the motor control system 10 to the component systems 18 to22. In addition, the transmission of data with respect to the status ofthe component systems 18 to 22 can be omitted when these systems arelogically connected to each other in such a manner that the transmitteddesired value already considers all operating states of the componentsystems 18 to 22, that is, when, for example, the transmission controlunit determines a corresponding desired value for the motor adjustmentfrom its own data, the commands of the ASR-control/MSR-control and/or ofthe chassis control in the sense of a superior control unit. Data istransmitted from the motor control system 10 to the component systems 18to 22 with respect to the actual value of the variable represented bythe desired value, for example, the clutch torque actual value(mokupact) or the actual value of the alternatively used variables, datawith respect to the maximum and minimal values of this variable(mokupmin, mokupmax), a value of this variable mokupfu made available bythe combustion as well as status data of the motor control such aswhether an intervention in the ignition adjustment or an intervention inthe metering of fuel, (for example interrupting injection) is possibleor with respect to the operating state of the motor (idle or overrun).

The number of the transmitted data can be reduced in dependence upon thefollowing: the configuration of the motor vehicle control system, theavailability of actuating variables and intervention possibilities andthe necessity of each piece of information. For example, the dataexchange of the driver command, of the maximum clutch torque andpossibly of the actual clutch torque can be omitted only for an ASRcontrol with injection intervention and ignition intervention withoutpossibility of electronic influencing of the air supplied.

A unified motor torque interface position can be realized by theinterface position according to the invention. This motor torqueinterface position realizes a slow changeable torque intervention viathe supply of air as well as a rapid torque intervention via injectionand ignition angle. The motor interface position is further configuredso as to be modular and, when an actuating variable is not available(for example, it is not possible to electrically adjust the supply ofair), only this component structure is not active without furtherintervention in the interface position.

The basic idea is to realize the desired power output or the desiredpower capacity (preferably the desired motor torque) by changing allmotor actuating variables which are available. These variables includethe air supply, ignition setting and metering of fuel. In today'ssystems, the supply of air is determined either directly by theaccelerator pedal or is adjustable electrically by providing electricaldecoupling from the accelerator pedal. In the first case, the driver hasadjusted the motor torque in the steady-state condition and the motorintervention of the ASR control or the transmission control then takesplace by changing the ignition setting and/or the metered fuel, forexample, by suppressing selected injection pulses. A desired motortorque mokupf is preset when the air supply is influencedelectronically, for example, by a higher-order level, a drive traincontrol or by the motor control system itself.

FIG. 3 shows the structure of a preferred embodiment of the unifiedmotor torque interface position in the area of the motor control. Adesired clutch torque mokupf from the driver and an intervention torquemokupdes from the component systems 18 to 22 as well as data withrespect to the status of available component systems (for example,whether ASR or MSR is activated) are transmitted to the motor control.

A block circuit diagram is selected as a means of illustrating theinterface position for reasons of clarity. Actually, the interfaceposition of the invention is realized as a computer program. In FIG. 3,the same parameters and functions are used at different locations of theblock circuit diagram. These parameters and functions are identified bythe same reference numerals or are only indicated for reasons of clarityof illustration. It is understood that only a function element havingthe corresponding function is present and the result is applied atdifferent locations of the computer program.

In FIG. 3, a drive unit 100 such as an internal combustion engine isshown which has assigned thereto symbolically illustrated units forcontrolling fuel metering 102, control of the ignition time point 104 aswell as control of the supply of air 106 via a throttle flap.Alternatively, the drive unit can be a diesel engine for which, as arule, the influencing of the air can be omitted or the drive unit can bean electric motor having the corresponding intervention possibilities.

FIG. 3 shows the interface position between the values supplied to themotor control system from the component systems, the values emitted bythe motor control system to the component systems and the interventionpossibilities which, as a rule, are present. These interventionpossibilities are on the air supplied, the fuel metered and the ignitiontime point. In conventional systems, the air supply is determined by thedriver as a consequence of the mechanical connection of the throttleflap with the accelerator pedal and can therefore not be influenced. Forthis reason, the "air path" 108 is enclosed by a broken line. The airpath 108 is provided in systems wherein the air supply can be adjustedelectrically. The term "air path" is used here to denote electroniccircuitry which operates to adjust the throttle flap in a gasolineengine. Stated otherwise, electronics are substituted for conventionalmechanical linkages.

A first line 110 conducts the clutch torque desired value mokupdes ofone of the component systems to a selector unit 112. This unit issupplied with the driver command mokupf via a line 114 as well as withstatus data of the component systems via a line 116. The selector unit112 carries out a minimal value selection or maximum value selection(for example, for ASR minimal selection and for MSR, maximum selection)of the desired torque values pregiven by the component systems and thedriver command on the basis of the status data. The correction units 118and 120 are connected downstream of the selector unit 112. The desiredvalue transmitted from the selector unit is corrected with lost torqueamounts moverl and consumer torque amounts mona of additional consumers.As known from the state of the art, the lost torques are determined froman adaptable characteristic field 122 from rpm and motor temperature andthe lost torques are determined from an adaptable characteristic field124 in dependence upon the operating state of ancillary aggregates suchas air conditioners, steering, transmission, et cetera. Lost torquemoverl and consumer torque mona are added to the desired value mokupdesin the correction units 118 and 120 which results in a desired value forthe indexed torque or the combustion torque movdes. This desiredcombustion torque value is determined on the basis of the driver commandor the intervention values of component systems and corresponds to adesired value which is to be adjusted under ideal conditions. For thisreason, the desired combustion torque value is corrected with the actualignition setting in a further correction unit 126 so that the desiredtorque amount movfudes is obtained as a result. This desired torqueamount has to be supplied by the charge (air supplied and fuel meteredat lambda=1). The correction is made by dividing the torque desiredvalue movdes by a function F dependent upon the difference between anoptimal ignition angle zwopt and the particular ignition angle pregivenby the ignition characteristic field. The ignition angle zwopt as wellas the pregiven ignition angle zwkf are read out of a characteristicfield (not shown) in dependence upon load and rpm.

The desired combustion torque component of the air setting movfudes isused for the charge-end torque setting. The desired combustion torquecomponent is determined in the manner described above.

The desired torque value movfudes is converted in a characteristic field128, which follows the correction unit 126, in combination with themotor rpm (n) into an air-mass desired value tldes. Air-mass desiredvalue tldes and the air-mass actual value tLHFM, which is detected, forexample, by a hot film air-flow sensor, are supplied to an air-masscontroller 130. The air-mass controller forms a measure for thedeviation of the actual value from the desired value with which thedesired value tldes is preferably multiplicatively corrected in acorrection unit 132. A correction unit 134 follows the correction unit132. In this correction unit 134, this desired value is also correctedin dependence upon motor temperature and supplied to the throttle-flapposition desired value characteristic field 136. There, a throttle-flapposition desired value dkdes for the setting of the throttle flap isformed on the basis of the corrected air-mass desired value. Thethrottle flap is adjusted by the electronic accelerator pedal system 138and, if necessary, in dependence upon further variables such as throttleflap actual position, et cetera. The setting of the fuel flow to bemetered takes place in a known manner on the basis of the air-mass valuetlhfm and the rpm (n).

The "air path" 108 is framed by a broken line and is not active whenthere is mechanical coupling between the accelerator pedal and thethrottle flap. The driver command mokupf is no longer read in by themotor control system and the torque value mokupfu is transmitted to theother component systems as a driver command when required. The torquevalue mokupfu is computed as described below on the basis of the charge(air/fuel mixture) of the internal combustion engine set by the driver.The torque value mokupfu is a measure for the combustion torquegenerated by the adjusted charge at a pregiven air/fuel ratio.

For the rapid motor intervention via ignition and/or fuel metering, itis likewise advantageous to split up the torque to be realized by themotor into a combustion torque (the mechanical energy generated by thecompression phase) and a lost torque (drag torque or energy consumed byfriction and throttle losses).

The intervention into the fuel to be metered takes place, as a rule, bysuppressing the fuel metering at least to individual cylinders duringspecific work strokes. This procedure is known in the following asinjection suppression. The injection suppression and the ignition angleintervention influence primarily the combustion torque mov of the engineless the loss or drag torque moverl in which friction and throttlelosses are combined. For this reason, in the determination of theintervention in the metering of fuel via injection suppression and inthe ignition angle by ignition angle correction, the desired clutchtorque mokupdes is converted with the motor drag torque moverl and theconsumer torque of ancillary aggregates mona into a combustion torquedesired value movdes as already explained with reference to the airpath.

The determination of the desired combustion torque movdes can alreadytake place in the component systems or in a higher-level control unitbecause the engine drag torque and the consumer torque are essentiallyconstant or can be adapted by known methods (see the state of the artmentioned above). In this way, no clutch torque desired value istransmitted to the engine control but instead a combustion torquedesired value. In the same manner, the motor power Pdes to be suppliedcan be determined in the component systems or in the higher-ordercontrol unit, and be transmitted to the engine control system. In thetwo last cases, the interface position then operates on the basis ofcombustion torque values or the engine power values.

The computation of the desired combustion torque is shown in FIG. 3 bythe elements having the reference numerals 110a, 118a, 120a, 122a and124a. The procedure corresponds to that described with respect to theair path. In the computation unit 140, which is downstream of theseelements, the combustion desired torque movdes is converted into ameasure for the ignition angle correction dzw and/or into a measure forthe injection suppression X, for example, by suppressing the injectionof X cylinders within a pregiven number of crank angle rotations (X canalso be less than 1). This conversion is made while considering thestatus data of the component system 116a and the combustion torqueamount movfu generated by setting the charge. The combustion torqueamount movfu is supplied via line 141 and is determined as will bedescribed in the following. The function defined by computation unit 140is a general function for determining ignition angle intervention and/orinjection intervention which is shown in the advantageous embodimentsaccording to FIGS. 4 to 6.

The combustion torque movfu generated by the charge of the air/fuelmixture is then a value for normal conditions (ignition angle pursuantto rpm/load characteristic field without ignition angle interventionwith the exhaust gas composition lambda=1).

A characteristic field 142 is known from German patent application4,232,974 and is a so-called charge model. The characteristic field 142forms a measure for the air mass flow tlact flowing to the engine fromthe rpm and air mass measured value tLHFM. This measure is convertedinto an optimal combustion torque value movopt in the next-downstreammotor characteristic field 144 in combination with the rpm and referredto the ignition angle zwopt which is optimal with respect to the poweror torque output. This value is corrected by a function F in thefollowing multiplication unit 146. This function F is dependent upon thedifference between the optimal ignition angle zwopt and thecharacteristic field angle zwkf (see block 126) which is to be selectedunder the particular operating conditions (no ignition angleintervention) which are just then present. The value corrected in thismanner corresponds to the combustion torque movfu generated by thecharge under normal conditions and which is supplied to thecharacteristic field 140.

The combustion torque value movfu determined in this manner is convertedinto a clutch torque value at the ignition field angle mokupfu. Thisconversion takes place while correcting (subtraction) with the torqueamounts by consumers mona determined as shown above as well as torquedrag value moverl in the correcting units 118b and 120b. The clutchtorque value is made available to the component systems via the line148.

The optimal combustion torque value movopt is determined in thecharacteristic field 144. This combustion torque value movopt isconverted into a measuring value for the clutch torque mokupact which isactually present and is supplied via the line 156, as required, to thecomponent systems. This conversion is achieved via correction with afunction F which is dependent upon the difference of the optimalignition angle zwopt and the actual adjusted ignition angle zwact (thatis, as required, while considering other corrections such as for knockcontrol or idle control) in a correction unit 150. This correction incorrection unit 150 is made while considering the possible suppressedinjections in the computation unit 152 as well as the subtraction ofconsumer torque amounts mona and loss torque amounts moverl in thecorrecting units 118c and 120c and while subtracting the torque amountdetermined in a computation unit 154a in dependence upon the motor rpmchanges.

In addition, the number of injections to be suppressed are supplied tothe injection system 102. This number is determined in characteristicfield 140 and the injection system 102 carries out the presetting, forexample, via a sequential suppression pattern. (In a sequentialsuppression pattern, fuel injection is, for example, suppressed to onecylinder and then to a next cylinder and so on.) The ignition anglecorrection value dzw is converted into a correction amount of thecharacteristic field ignition angle dzwkf and is supplied to theignition system 104 for adjustment. This conversion takes place in afirst correcting unit 158 and in a second correcting unit 160 bysubtracting the optimal ignition angle zwopt and adding thecharacteristic field ignition angle zwkf.

In this context, it should be noted that the interface positiondescribed in FIG. 3 describes all three influence possibilities on thepower parameter of the motor. In advantageous embodiments, all of thesethree parameters can be influenced electronically so that the interfaceposition can be realized in the manner shown. The formulas shown belowapply to the computations in the block 140 for determining the ignitioncorrection and/or the suppressions.

In other embodiments, however, only ignition angle intervention (FIG. 4)and/or injection suppressions (FIGS. 5 and 6) can be considered withoutelectrical intervention possibilities in the supply of air. Even inthese embodiments, the interface position structure shown in FIG. 3 canbe applied unchanged in an advantageous manner with respect to availableintervention possibilities. The block 108 enclosed by the broken line isomitted when the air is not influenced. The injection path and block 152are omitted for exclusive ignition intervention (see FIG. 4) and forexclusive injection intervention (see FIG. 5), the correction of theignition angle is omitted (blocks 158, 168 are omitted, blocks 150 and146 are combined since zwkf=zwact). A configuration according to FIG. 6is provided when ignition suppression and intervention with respect toignition angle are considered.

Since the blocks satisfy the same functions as in FIG. 3, these blocksare provided with the same reference numerals and a description thereofis omitted and reference can be made to the description corresponding toFIG. 3.

A simplification of the interface position can be achieved by reducingthe complexity of the characteristic fields and characteristic lines(for example, 122, 124, 128, 130, 140, 142, 144, et cetera). In thisway, an interface position of any desired complexity can be realizedwithout it being necessary to undertake interventions into the basicstructure of the interface position.

In the following, the operation of the interface position will bedescribed in greater detail with respect to various embodiments.

A torque reduction command is first described. If a rapid torqueintervention is required, then this takes place by comparing the wantedcombustion torque movdes and the combustion torque movfu generated undernormal conditions by the charge. If movdes is less than movfu, thetorque reduction takes place by changing the ignition angle and/or bysuppressing injection pulses. The value movdes is less than movfu, forexample, for an ASR intervention or as a consequence of a correspondingreduction command of the transmission control. A slower intervention forreduction takes place via the adjustment of the air supply. Here,various strategies for the ignition angle intervention and for thepattern of the injection suppression can be pursued. An adjustment ofthe supply of air in accordance with movdes takes place in parallel viathe air path 108 when intervention is possible and, when an interventionis not possible, the air supply corresponds to the driver command and isconsidered in the value movfu.

First, the case is described wherein only the ignition angleintervention is possible (see FIG. 4). In this case, the relationshipbetween the combustion torque desired value movdes and the ignitionangle correction dzw is given by the following equation:

    movdes=movopt*F(dzw)                                       (1)

wherein F(dzw) defines the torque reduction factor in dependence uponthe ignition angle correction (in the form of a characteristic line)referred to the optimal ignition angle and is stored in a characteristicline and wherein dzw defines the difference between the desired ignitionangle and the optimal ignition angle. The block 140 is connected via theline 141 to the output line of the block 144. This corresponds to thegeneral configuration of FIG. 3 wherein movfu defines the basis of thecomputation of the ignition intervention and the injection intervention.

The ignition angle correction value dzw is referred to the optimalignition angle zwopt and results then from the inverse factor inaccordance with the following equation:

    dzw=F.sup.-1 (movdes/movopt)                               (2)

This computed value is limited to the maximum permitted ignition anglecorrection dzwmax which is a function of the inducted air mass and therpm so that it is ensured that the mixture inducted by the cylinder canstill be ignited. Thereafter, the ignition angle correction value dzwkfis determined referred to the characteristic field ignition angle of theignition adjusting system zwkf by subtraction of the optimal ignitionangle and addition of the characteristic field ignition angle (seeequation 3). The characteristic ignition field angle zwkf is understoodto be the ignition angle which would adjust itself without ignitionangle intervention by the torque interface position.

    dzwkf=dzw-zwopt+zwkf                                       (3)

No large torque change can be realized only with the ignition anglecorrection. For this reason, an application of the method with anexclusive ignition angle correction in combination with an electronicaccelerator pedal system is advantageous since, in this case, only arapid reaction is intended to be obtained with the ignition anglecorrection. The adjustment of the air supplied and the correction of theignition angle take place simultaneously in this case.

The torque reduction by exclusive intervention into the fuel metering bysuppressing injection pulses offers a second possibility (see FIG. 5). Acertain number of so-called suppression stages is provided. The Zsuppression stages determine the number of the maximum possible stagesof suppression of the cylinders. For example, for a four-cylinderengine, eight suppression stages are provided wherein individualcylinders are suppressed in accordance with the suppression stages overfour crankshaft rotations (first stage, suppression of 0.5 cylinder;second stage, one cylinder; third stage 1.5 cylinder, et cetera). Theeighth suppression stage can correspond to a complete suppression. Anydesired factor of cylinder number is possible and is selected inaccordance with the desired torque gap between two stages, that is, thedifference of the torques in two mutually adjacent stages.

With the determination of the combustion torque supplied by the motorfor suppressed cylinders, a certain number of crankshaft rotations mustbe averaged with the number of the crankshaft rotations corresponding tothe number of the available suppression stages. This would be fourcrankshaft rotations in the above example.

The relationship between the desired combustion torque movdes and thecombustion torque movfu generated by the adjusted air supply results asfollows for X suppressed cylinders (suppression stage X) for Z possiblesuppression stages and for the characteristic field ignition angle zwkf,which remains constant at least for the cylinders which are notsuppressed:

    movdes=(1-X/Z)*movfu                                       (4)

In equation (4), it should be considered that the component to thecombustion torque movfu from a suppressed cylinder is zero. If the aboveequation is solved for X, then there results the suppression stagesuitable for making available the desired combustion torque or thesuitable number of cylinders to be suppressed via a pregiven crankshaftangle:

    X=Z*(movfu-movdes)/movfu                                   (5)

The computed value of X (see block 140) must then be rounded off inorder to obtain a permitted or available suppression stage. By roundingout upwardly, a somewhat larger reduction compared to the desired torquereduction is obtained so that this can be a preferred measure.

The injection suppression pattern is most often carried out as asequential pattern so that each cylinder is not supplied with fuelwithin a pregiven time in accordance with the extent of the injectionsuppression. This improves running of the engine and prevents a toointense cooling off of the cylinders which are switched off.

The intervention in the metering of fuel and in the ignition angle is afurther embodiment for reducing torque (see FIG. 6). In this connection,it should be noted that in FIG. 6, an effective combustion torque moveis used in lieu of the use of the value movfu in block 140. Thecombustion torque move already considers the suppression of cylindersreferred to the optimal ignition angle. This defines only anotherpossibility of computation. The suppressed cylinders are taken intoaccount for the determination of the combustion torque in block 140 inthe embodiment of FIG. 3.

The torque reduction results from a combination of the above-mentionedcases by means of the following equation:

    movdes=(1-X/Z)*movopt*F(dzw)                               (6)

Two strategies can be pursued for determining the desired combustiontorque.

For the first strategy, a higher priority can be assigned to theignition angle intervention than to the injection suppression in orderto, for example, reduce the exhaust gas emission. This means that theignition angle intervention is permitted in dependence upon pregivenclutch torque desired values up to its maximum permitted ignition anglechange dzwmax and only then, when a still greater torque reduction isdemanded, suppression of cylinders is permitted. For this reason, firstthe number of the reduction stages according to equation (6) is set to 0and the ignition angle correction dzw is computed as in the case of theexclusively available ignition angle correction according to equation(2). If the ignition correction value is less than the pregiven maximumvalue, then no injection suppression takes place and the ignition angleintervention takes place as described above. However, if it has beenrecognized that the ignition angle correction value dzw is greater thanthe maximum pregiven correction value, then the number of cylinders tobe suppressed is computed according to equation (6) by inserting themaximum ignition angle correction value dzwmax and is defined by thefollowing equation:

    X=Z*(movopt*F(dzwmax)-movdes)/(movopt*F(dzwmax))           (7)

The pregiven number of cylinders is suppressed by rounding off in theupward direction and selecting the suppression pattern. If a veryprecise realization of the desired clutch torque is required, then thevalue of the number of suppressed cylinders is again inserted into theabove equation (6) and an ignition angle correction value dzw isdetermined in accordance with the following equation:

    dzw=F.sup.-1 (movdes/(movopt*(1-X/Z)))                     (8)

In the above case, the injection suppression pattern can be coarse andcan, for example, be limited to a number of stages corresponding to thecylinder number. The torque gap occurring between two suppression stagesis compensated by the ignition angle correction. Equation (8) describedabove applies only when the number X is less than the total number Z ofthe suppression stages. If these two values are equal, then no ignitionangle correction takes place and the motor reaches its minimum torquemokupmin which contains the lost torque because of drag torque andancillary consumers. A further reduction of the drive power is notpossible by a motor intervention and must take place, for example, bybraking intervention or transmission intervention. Here, it should beconsidered that for motor vehicles wherein the air supply is influencedelectrically, an adjustment of the air takes place at the same time asan adjustment of fuel and ignition.

The second strategy provides that the injection suppression has a higherpriority than the ignition angle intervention. With this strategy, theignition angle correction is used only for fine metering of the motortorque between two suppression stages.

In this procedure, the ignition angle correction value dzw is set inequation (6) to the difference between the optimal ignition angle andthe characteristic field ignition angle. The number of cylinders X to besuppressed then results from equation (5). This value is rounded down toa whole integer and thereafter, the ignition angle correction value dzwis computed from equation (8) by inserting the number of the cylinders Xto be suppressed. The ignition angle correction value is then placedinto relationship to the characteristic field ignition angle and thecharacteristic field ignition correction value in accordance withequation (3). From the computed number of cylinders to be suppressed, asuppression pattern is determined and realized by the injection system.Here, the number of stages of the injection suppression can also besmall, especially, the number of stages can correspond to the cylindernumber. The torque gap between two stages is compensated by the ignitionangle correction.

A comparable procedure is undertaken with a torque increase command, forexample, by an MSR intervention or by the transmission control.

Here, the clutch desired torque mokupdes (movdes) is greater than thetorque amount mokupfu (movfu) generated by the charge under normalconditions. The rapid torque build-up can only take place by ignitionangle change up to the optimal ignition angle zwopt or up to the knocklimit. A torque increase above an ignition angle change can no longer beobtained since the characteristic field ignition angle lies mostly closeto the optimal ignition angle. The requirement of rapid torque increasefrom MSR can be obtained in overrun in that the number of cylinders tobe suppressed is computed according to equation (5) and the differencebetween the maximum number of suppressed stages and the number ofcylinders to be suppressed is inserted. The overrun switchoff iseliminated by the MSR.

Preferably, the requirement of the torque increase can be realized inthat a clutch torque mokupdes is adjusted via the air path (idlecontroller or electronic accelerator pedal, see FIG. 3). In the case ofidle, basically no external motor intervention is permitted. The idledata, as also, for example, the overrun data, during which no ASRintervention is possible, is supplied to the component systems via theinterface position.

The motor drag torque moverl is made up of the motor friction loss andthe motor throttle loss and is dependent upon engine temperature, enginerpm and intake-pipe pressure. This value can advantageously be broken upinto a drag torque for intake-pipe pressure 0 (closed throttle flap, airflow 0) and into a torque correction dmoverl in dependence uponintake-pipe pressure:

    moverl=moverl(Ps=0)-dmoverl(Ps)                            (9)

The drag torque for a closed throttle flap can likewise advantageouslybe broken up into a drag torque dependent upon the motor rpm and into adrag torque dependent upon motor temperature and is adapted in idle inaccordance with the state of the art. The torque requirement ofancillary equipment is determined in correspondence to this state of theart. The correcting variable of the drag torque can be determined independence upon the intake-pipe pressure by interpolation of acharacteristic line. When no pressure sensor for measuring theintake-pipe pressure is present, then the intake-pipe pressure issubstituted for by the product of the intake-pipe temperature and thecharge since the intake pressure is proportional to the product ofcharge and intake-pipe temperature.

The actual motor torque mokupact is computed from the actually realizednumber of suppressed cylinders X and the ignition angle actual value inaccordance with equation (6) while considering the drag torque and thetorque amounts of the ancillary equipment or the inertial torque of themotor.

This value together with the minimum torque mkupmin (=-(moverl+mona))and the clutch torque mkupfu prepared by the charge under normalconditions is preferably supplied to other control apparatus. Themaximum obtainable clutch torque mokupmax which is obtainable is alsosupplied to other control apparatus while considering the instantaneousair density. The clutch torque mokupfu under normal conditions servesthen as a reference point for the control in other control apparatus,for example, for ASR, a maximum permissible clutch torque mozul iscomputed from the wheel slippage. If this value is less than the clutchtorque under normal conditions, the ASR status bit is set and thepermissible clutch torque is transmitted to the motor control as theclutch torque desired value. When the permissible clutch torque isgreater than the clutch torque available under normal conditions, theASR status bit is reset and the intervention is terminated. For MSR, theprocedure is the opposite as with ASR.

With the transmission control, a desired rapid torque increase can berealized in an advantageous manner during gear shifting in that thetransmission control presets the torque desired after the gear-shiftingoperation via the driver command, however, the clutch torque to beactually realized during the gear-shifting operation is emitted via thetorque intervention mokupdes. Here, the clutch torque mokupfu, realizedby the charge under normal conditions, is greater than theinstantaneously required clutch torque mokupdes. The torque differencebetween these two values is compensated by the ignition angle correctionand the increase of the actual clutch torque in response to the drivercommand is realized after gear shifting by cancelling the ignition anglecorrection.

The correction of the combustion torque movopt for an optimal ignitionangle from a torque characteristic field is, for various motor rpms,essentially linear in dependence upon the charge tlact and can besimplified advantageously for less precise requirements as follows:

    movopt=tlact*G(n)                                          (10)

or:

    movopt=tlact*G                                             (11)

G(n) defines a rpm-dependent factor which is essentially determined bythe rpm-dependent combustion efficiency and can be replaced by a meanfactor without rpm dependency with further reduction of precision.

A corresponding procedure can be applied advantageously in combinationwith alternative drive concepts such as hydrogen motors.

It is understood that the foregoing description is that of the preferredembodiments of the invention and that various changes and modificationsmay be made thereto without departing from the spirit and scope of theinvention as defined in the appended claims.

What is claimed is:
 1. A method for controlling an internal combustionengine of a motor vehicle to which fuel is metered, the engine having: apredetermined number of cylinders, an ignition angle which can beshifted to provide an adjustment thereof and an adjustable air flow tothe engine, the engine being equipped with an electronic controlapparatus for controlling the torque of the engine by at leastinfluencing: the metering of fuel to the engine, the adjustment of theignition angle of the engine and said air flow, the method comprisingthe steps of:providing an input desired value (mokupdes) of a desiredtorque of said engine; converting said input desired value (mokupdes)into a desired value (Dkdes) for adjusting said air flow to the engine;determining an actual value (movopt, movfu) for said torque of saidengine; determining at least one of the following variables inaccordance with said desired value of torque (mokupdes) and said actualvalue (movopt, movfu) of said torque: the number (X) of said cylindersto which the metering of fuel is to be suppressed or permitted; and, theangle (dzwkf) by which said ignition angle is to be shifted; and,controlling said actual value (movopt, movfu) of said torque to approachsaid desired value (mokupdes) by adjusting said air flow based on saiddesired value (DKdes) and by performing at least one of the followingoperations:(a) suppressing or permitting the metering of fuel to saidnumber (X) of said cylinders; and, (b) shifting the ignition angle ofthe engine by said angle (dzwkf).
 2. The method of claim 1, wherein themotor vehicle has at least two component systems interconnected via acommunication system for facilitating an exchange of data between thecomponent systems, a first one of said component systems being saidcontrol apparatus for controlling said engine which develops torque fordriving the vehicle, the method comprising the further stepsof:providing an input desired value (mokupdes) indicative of the desiredtorque to be outputted by said engine from a second one of saidcomponent systems; transmitting said input desired value (mokupdes) fromsaid second component system via said communication system to saidcontrol apparatus.
 3. The method of claim 1, wherein said enginegenerates a combustion torque, and said input desired value (mokupdes)represents a desired value of said combustion torque.
 4. The method ofclaim 1, wherein the engine generates power, and said input desiredvalue (mokupdes) represents a desired value of said power.
 5. The methodof claim 1, wherein said input desired value (mokupdes) variescontinuously and said control unit continuously converts said inputdesired value (mokupdes) to adjust said torque to correspond thereto. 6.The method of claim 1, wherein said engine and the motor vehicle haveoperating variables which characterize the operation thereof, the methodcomprising the further steps of:collecting data as to at least one ofthe operating variables of said engine and said motor vehicle which isindicative of the torque actually outputted by said engine; performing acomputation in said control apparatus based on said collected data toobtain an output actual value (mokupact) indicative of the actual valueof said torque outputted by said engine as determined from the collecteddata; and, transmitting said output actual value (mokupact) to saidsecond component system via said communications system.
 7. The method ofclaim 1, wherein the vehicle includes a clutch providing a clutch torquesupplied by said engine and wherein said input desired value (mokupdes)represents a desired value of said clutch torque to be outputted by saidengine.
 8. The method of claim 1, wherein said vehicle includes at leastone of the following component systems: a component system for carryingout an anti-skid control, a component system for carrying out an enginebraking control, a component system for carrying out a transmissioncontrol and a component system for carrying out a suspension control. 9.The method of claim 1, wherein fuel is metered to the engine and whereinthe method comprises the further step of converting said input desiredvalue into a corresponding adjusting value for controlling at least oneof the following: said ignition angle and the metering of fuel to theengine.
 10. The method of claim 1, wherein said vehicle includes meansfor collecting status data as to said operating state and wherein one ofsaid component systems transmits said status data to said firstcomponent system; and, said first component system adjusts the actualtorque in accordance with said status data.
 11. A system for controllingan internal combustion engine of a motor vehicle, the engine generatinga torque to propel said vehicle and having a predetermined number ofcylinders and an adjustable ignition angle, the system comprising:meansfor adjusting fuel metered to said engine; means for adjusting saidignition angle; means for adjusting air flow to said engine; a controlapparatus for controlling said torque by operating upon at least one ofsaid means for adjusting the fuel metered to the engine, said means foradjusting said ignition angle and said means for adjusting said airflow; a communication system for interconnecting said control apparatus,said fuel adjusting means and said ignition angle adjusting means; and,said control apparatus having a microcomputer including thefollowing:(a) means for receiving a desired value (mokupdes) for saidtorque of said engine; (b) means for converting said desired value(mokupdes) into a desired value (DKdes) of said air flow; (c) means fordetermining an actual value (movopt, movfu) for said torque of saidengine; (d) means for determining at least one of the followingvariables in accordance with said desired value of torque (mokupdes) andsaid actual value (movopt, movfu) of said torque: the number (X) of saidcylinders to which the metering of fuel is to be suppressed orpermitted; and, the angle (dzwkf) by which said ignition angle is to beshifted; (e) means for controlling said actual value (movopt, movfu) oftorque to approach said desired value (mokupdes) by adjusting said airflow based on said desired value (DKdes) and by doing at least one ofthe following:(i) suppressing or permitting the metering of fuel to saidnumber (X) of said cylinders; and, (ii) shifting the ignition angle ofthe engine by said angle (dzwkf).
 12. A system for controlling aninternal combustion engine of a motor vehicle, the engine generating atorque to propel said vehicle and having a predetermined number ofcylinders, the system comprising:means for metering fuel to said engine;means for adjusting air flow to said engine; a control apparatus forcontrolling said torque by operating on said fuel-metering means; acommunication system for interconnecting said control apparatus and saidfuel-metering means; and, said control apparatus having a microcomputerincluding:(a) means for receiving a desired value (mokupdes) of saidtorque of said engine; (b) means for converting said desired value(mokupdes) into a desired value (DKdes) of said air flow; (c) means fordetermining an actual value (movopt, movfu) of said torque of saidengine; (d) means for determining a variable in the form of a number (X)of said cylinders to which metering of fuel is suppressed or permittedin accordance with said desired value (mokupdes) and said actual value(movopt, movfu); and, (e) means for operating on said fuel-meteringmeans to adjust the fuel metered to the engine on the basis of saidvariable and adjusting said air flow based on said desired value (DKdes)thereby controlling said engine by causing said actual value (movopt,movfu) of torque to approach said desired value (mokupdes) of torque.13. The system of claim 12, wherein air is supplied to the engine andthe system further comprising at least one of the following plurality ofcomponent systems: a drive-slip control unit; an engine drag torquecontrol unit; a transmission control unit; a suspension control unit;and, each of said component systems having means for emitting aninstantaneous command to said control apparatus for said torque which isconditioned by correcting any one of: the fuel metered to said engineand the air supplied to said engine.
 14. A system for controlling aninternal combustion engine of a motor vehicle, the engine generating atorque to propel said vehicle and having an adjustable ignition angle,the system comprising:means for adjusting said ignition angle; means foradjusting air flow to said engine; a control apparatus for controllingsaid torque by operating on said means for adjusting said ignitionangle; a communication system for interconnecting said control apparatusand said ignition angle adjusting means; and, said control apparatushaving a microcomputer including:(a) means for receiving a desired value(mokupdes) of said torque of said engine; (b) means for determining anactual value (movopt, movfu) of said torque of said engine; (c) meansfor converting said desired value (mokupdes) into said quantity foradjusting the air supplied to said engine; (d) means for determining avariable in the form of an angle (dzwkf) by which said ignition angle isto be shifted in accordance with said desired value (mokupdes) and saidactual value (movopt, movfu); and, (e) means for operating on saidignition angle adjusting means to adjust said ignition angle on thebasis of said variable and for adjusting said air flow based on saiddesired value (DKdes) thereby controlling said engine by causing saidactual value (movopt, movfu) of torque to approach said desired value(mokupdes) of torque.
 15. The system of claim 14, wherein air issupplied to the engine and the system further comprising at least one ofthe following plurality of component systems: a drive-slip control unit;an engine drag torque control unit; a transmission control unit; asuspension control unit; and, each of said component systems havingmeans for emitting an instantaneous command to said control apparatusfor said torque which is conditioned by correcting any one of: theignition angle and the air supplied to said engine.
 16. A system forcontrolling an internal combustion engine of a motor vehicle, the enginegenerating a torque to propel said vehicle and having a predeterminednumber of cylinders and an adjustable ignition angle, the systemcomprising:means for adjusting fuel metered to said engine; means foradjusting said ignition angle; means for adjusting the air flow to saidengine; a control apparatus for controlling said torque by operatingupon said means for adjusting the fuel metered to the engine and saidmeans for adjusting said ignition angle; a communication system forinterconnecting said control apparatus, said fuel adjusting means andsaid ignition angle adjusting means; and, said control apparatus havinga microcomputer including the following:(a) means for receiving adesired value (mokupdes) for said torque of said engine; (b) means fordetermining an actual value (movopt, movfu) for said torque of saidengine; (c) means for converting said desired value (mokupdes) into saidquantity for adjusting the air supplied to said engine; (d) means fordetermining, in accordance with said desired value (mokupdes) of saidtorque and said actual value (movopt, movfu) of said torque, thefollowing variables: the number (X) of said cylinders to which themetering of fuel is to be suppressed or permitted; and, the angle(dzwkf) by which said ignition angle is to be shifted; and, (e) meansfor controlling said actual value (movopt, movfu) of torque to approachsaid desired value (mokupdes) on the basis of said variables byadjusting said air flow based on said desired value (DKdes) and by doingthe following:(i) suppressing or permitting the metering of fuel to saidnumber (X) of said cylinders; and, (ii) shifting the ignition angle ofthe engine by said angle (dzwkf).
 17. The system of claim 16, whereinair is supplied to the engine and the system further comprising at leastone of the following plurality of component systems: a drive-slipcontrol unit; an engine drag torque control unit; a transmission controlunit; a suspension control unit; and, each of said component systemshaving means for emitting an instantaneous command to said controlapparatus for said torque which is conditioned by correcting any one of:the ignition angle, the fuel metered to said engine and the air suppliedto said engine.